High-quality BN films materials prepared by KAIST

Recently,a versatile method to transfer-print high-quality BN films composed of densely stacked BN nanosheets based on a desolvation‐induced adhesion switching (DIAS) mechanism is developed by Korea Academy of Science and Technology (KAIST).

Nano-hexagonal boron nitride (BN) is a new type of ceramic material with excellent performance and great development potential, and it has received extensive attention in recent years. It has the characteristics of high temperature oxidation resistance, radiation resistance, high thermal conductivity, high temperature lubricity, dielectric properties and good insulation properties. It is one of the important materials for heat dissipation materials and is widely used in metallurgy, aerospace, electronics and nuclear industries, etc. field. However, its application is limited by the current synthesis process.

The DIAS method developed by the researchers uses a urea-assisted ball milling method to modify the hydroxy functional groups on the edges of the BN material and peel off to obtain BN nanosheets. Then the ball-milled BN nanosheets are washed with water, dialysis and ultrasonic treatment, followed by vacuum filtration to obtain BN film materials.

It is shown that edge functionalization of BN sheets and rational selection of membrane surface energy combined with systematic control of solvation and desolvation status enable extensive tunability of interfacial interactions at BN–BN, BN–membrane, and BN–substrate boundaries. Therefore, without incorporating any additives in the BN film and applying any surface treatment on target substrates, DIAS achieves a near 100% transfer yield of pure BN films on diverse substrates, including substrates containing significant surface irregularities. The printed BNs demonstrate high optical transparency (>90%) and excellent thermal conductivity (>167 Wm⁻¹ K⁻¹) for few-micrometer-thick films due to their dense and well-ordered microstructures.

In conclusion, this study provides a strategy for preparing high-quality boron nitride thin films, which will play a more significant and important role in the next generation optoelectronic devices.

References: Yujin Han, Hyeuk Jin Han, Yoonhyuk Rah, Cheolgyu Kim, Moohyum Kim, Hunhee Lim, Kwang Ho Ahn, Hanhwi Jang, Kyoungsik Yu, et al. Desolvation-Triggered Versatile Transfer-Printing of Thermal Pure BN Films with–Optical Dual Functionality, Adv. Mater. 2020.DOI: 10.1002/adma.202002099